Technical Abstract:
Shell quality has been identified as a heritable trait which can be manipulated by genetic selection. Previous research has concluded that many methods of determining shell quality produce variable results. With the development of newer, more precise measuring technologies, shell strength can now be assessed in a consistent, objective fashion. A research project was conducted to determine what role shell strength might play in affecting external Salmonella Enteritidis (SE) contamination of egg contents. Visibly clean eggs were collected from an in-line shell egg processing facility at the accumulator. Eggs were inoculated by dipping in a concentrated suspension of nalidixic acid resistant SE. After storage, eggs were assessed for shell strength and both external and internal SE contamination. In the first study, there was a significant difference (P < 0.05) in shell strength amongst the three replicates. No differences between treatments were found for shell strength or SE contamination of contents. In the second study, there were no replicate differences for any of the monitored factors. When rinsate and content samples were enriched, 100 % of the rinsates were positive for SE. No content samples were shown to be SE contaminated during direct plating, but 3-5 % of the samples from each replicate were positive after enrichment. Correlation analysis of the results from each study found only weak correlations between shell strength and eggshell surface or contents SE contamination. Within the range of shell strengths recorded in this study, the correlation analysis suggests that shell strength does not play a major role in SE contamination.